Sealing system for forming thermal seals and methods of operation thereof

Abstract

The invention is a sealing system and a method of operation thereof. A sealing system which forms spaced apart thermal seals along a moving at least one web ( 60 ) by contact of the moving the at least one web with heated portions ( 74 ) of sealing elements ( 56 ) mounted on a sealing wheel ( 50 ) during rotation in accordance with the invention includes seal forming elements ( 56 ) which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web; and wherein each seal forming element has an outer section ( 62 ) on which is located at least one electrical heater ( 78 ), an inner section ( 64 ) which contacts the sealing wheel and an intermediate section ( 70 ) which includes thermal insulation ( 68 ) which insulates the outer section from the inner section.

1. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:
 seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web; and wherein  
 each seal forming element has an outer section, an inner section which contacts the sealing wheel and an intermediate section which includes thermal insulation which thermally insulates the outer section from the inner section; and  
 an electrical heater wholly disposed on each outer section for heating said outer section to form seals in said web contacting said outer sections.  
 
     
     
       2. A sealing system in accordance with  claim 1  wherein:
 each seal forming element is radially adjustable to vary the spacing between the spaced apart thermal seals.  
 
     
     
       3. A sealing system in accordance with  claim 2  wherein:
 each electrical heater comprises a film electrical resistance.  
 
     
     
       4. A sealing system in accordance with  claim 2  wherein:
 the outer section is parallel to an axis of rotation of the sealing wheel and the electrical heater extends longitudinally along the outer section.  
 
     
     
       5. A sealing system in accordance with  claim 2  wherein:
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       6. A sealing system in accordance with  claim 1  wherein:
 each electrical heater comprises a film electrical resistance.  
 
     
     
       7. A sealing system in accordance with  claim 6  wherein:
 the outer section is parallel to an axis of rotation of the sealing wheel and each electrical resistance extends longitudinally along the outer section.  
 
     
     
       8. A sealing system in accordance with  claim 1  wherein:
 the outer section is parallel to an axis of rotation of the sealing wheel and the electrical heater extends longitudinally along the outer section.  
 
     
     
       9. A sealing system in accordance with  claim 1  wherein:
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       10. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of an outside periphery of a sealing wheel during rotation comprising:
 seal forming elements attached to the sealing wheel which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web; and wherein  
 each seal forming element has an outer section which peripherally contacts the at least one web and includes a film resistance electrical heater facing the at least one web and thermal insulation disposed between the outer section and the sealing wheel which insulates the outer section from the sealing wheel.  
 
     
     
       11. A sealing system in accordance with  claim 10  wherein:
 the seal forming elements comprise a first group which are parallel to an axis of rotation of the sealing wheel, and  
 a second group which are disposed circumferentially on an outside periphery of the sealing wheel and are individually disposed between different pairs of adjacent seal forming elements of the first group.  
 
     
     
       12. A sealing system in accordance with  claim 11  wherein:
 the first and second groups are continuous and joined together.  
 
     
     
       13. A sealing system in accordance with  claim 12  wherein:
 the film resistance is a thick film resistance which varies along a longitudinal dimension of at least one of the first and second groups.  
 
     
     
       14. A sealing system in accordance with  claim 13  wherein:
 the thick film resistance is comprised of a plurality of sections of resistance with at least two of the sections being of a different resistance in at least one of the first and second groups.  
 
     
     
       15. A sealing system in accordance with  claim 14  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening ink one of the at least two sections.  
 
     
     
       16. A sealing system in accordance with  claim 13  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       17. A sealing system in accordance with  claim 12  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       18. A sealing system in accordance with  claim 11  wherein:
 the film resistance is a thick film resistance which varies along a longitudinal dimension of at least one of the first and second groups.  
 
     
     
       19. A sealing system in accordance with  claim 18  wherein:
 the thick film resistance is comprised of a plurality of sections of resistance with at least two of the sections being of a different resistance in at least one of the first and second groups.  
 
     
     
       20. A sealing system in accordance with  claim 19  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       21. A sealing system in accordance with  claim 18  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       22. A sealing system in accordance with  claim 11  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       23. A sealing system in accordance with  claim 10  wherein:
 the film resistance is a thick film resistance which varies along a longitudinal dimension thereof.  
 
     
     
       24. A sealing system in accordance with  claim 23  wherein:
 the thick film resistance of each sealing element is comprised of a plurality of sections of resistance with at least two of the sections being of a different resistance.  
 
     
     
       25. A sealing system in accordance with  claim 24  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       26. A sealing system in accordance with  claim 23  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       27. A sealing system in accordance with  claim 10  wherein:
 the film resistance is a thick film resistance which varies along a longitudinal dimension of at least one of the first and second groups.  
 
     
     
       28. A sealing system in accordance with  claim 27  wherein:
 the thick film resistance is comprised of a plurality of sections of resistance with at least two of the sections being of a different resistance in at least one of the first and second groups.  
 
     
     
       29. A sealing system in accordance with  claim 28  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       30. A sealing system in accordance with  claim 27  wherein:
 the first group includes at least one section of resistance disposed between ends thereof which is wider than the resistance at the ends which produces a seal dividing a container defined between adjacent elements of the first group and an element of the second group into at least two sections with the at least one section of resistance which is wider between adjacent elements producing a seal defining an opening into one of the at least two sections.  
 
     
     
       31. A sealing system which forms spaced apart thermal seals between at least two webs by contact of the at least two webs with heated seal forming elements comprising:
 a pair of seal forming elements which contact opposed sides of the at least two webs to form the thermal seals by heat transfer to the at least one web; and wherein  
 each of the pair of seal forming elements has a first section which contacts one of at least two webs and includes a film resistance electrical heater facing one of the at least two webs and thermal insulation disposed between the first section and a second section which is spaced farther from the at least two webs than the first section with the seal forming elements having a closed periphery for containing a substance inside the closed periphery between the at least two webs.  
 
     
     
       32. A sealing system in accordance with  claim 31  wherein:
 the resistance is a thick film resistance and the insulation is a plurality of slots located at different sides of each seal forming element with each slot providing an air gap between the film heating element and the second section.  
 
     
     
       33. A sealing system in accordance with  claim 31  wherein:
 the resistance is a thick film resistance and the insulation is a peripheral ring of thermal insulation extending around a periphery of each seal forming element.  
 
     
     
       34. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:
 seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web;  
 each seal forming element having an outer section, on which is located at least one electrical heater, an inner section which contacts the sealing wheel and an intermediate section which includes thermal insulation which thermally insulates the outer section from the inner section;  
 each electrical heater being comprised of an electrical resistance disposed along a longitudinal dimension of the outer section of the seal forming element, the electrical resistance being distributed along the longitudinal dimension with a higher electric resistance being adjacent to a part of the intermediate section through which heat flows to the inner section and a lower electrical resistance which is disposed adjacent to the thermal insulation of the intermediate section; and wherein  
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       35. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:
 seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web;  
 each seal forming element having an outer section, on which is located at least one electrical heater, an inner section which contacts the sealing wheel and an intermediate section which includes thermal insulation which thermally insulates the outer section from the inner section;  
 each electrical heater being comprised of an electrical resistance disposed along a longitudinal dimension of the outer section of the seal forming element, the electrical resistance being distributed along the longitudinal dimension with a higher electric resistance being adjacent to a part of the intermediate section through which heat flows to the inner section and a lower electrical resistance which is disposed adjacent to the thermal insulation of the intermediate section;  
 the inner section of each seal forming element is joined to upper and lower parts of the sealing wheel which are separated on an axis of rotation of the wheel;  
 the higher electrical resistance is located proximate to the upper and lower parts of the wheel and the lower electrical resistance separates the higher electrical resistance proximate to the upper and lower parts; and wherein  
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       36. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:
 seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web;  
 each seal forming element having an outer section, on which is located at least one electrical heater, an inner section which contacts the sealing wheel and an intermediate section which includes thermal insulation which thermally insulates the outer section from the inner section;  
 each electrical heater being comprised of an electrical resistance disposed along a longitudinal dimension of the outer section of the seal forming element, the electrical resistance being distributed along the longitudinal dimension with a higher electric resistance being adjacent to a part of the intermediate section through which heat flows to the inner section and a lower electrical resistance which is disposed adjacent to the thermal insulation of the intermediate section;  
 each seal forming element being radially adjustable to vary the spacing between the spaced apart thermal seals; and wherein  
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       37. A sealing system which forms spaced apart thermal seals along at least one moving web by contact of the moving at least one web with heated portions of sealing elements mounted on a sealing wheel during rotation comprising:
 seal forming elements which peripherally contact the at least one web to form the thermal seals by heat transfer to the at least one web;  
 each seal forming element having an outer section, on which is located at least one electrical heater, an inner section which contacts the sealing wheel and an intermediate section which includes thermal insulation which thermally insulates the outer section from the inner section;  
 each electrical heater being comprised of an electrical resistance disposed along a longitudinal dimension of the outer section of the seal forming element, the electrical resistance being distributed along the longitudinal dimension with a higher electric resistance being adjacent to a part of the intermediate section through which heat flows to the inner section and a lower electrical resistance which is disposed adjacent to the thermal insulation of the intermediate section;  
 the inner section of each seal forming element being joined to upper and lower parts of the sealing wheel which are separated on an axis of rotation of the wheel; and  
 the higher electrical resistance being located proximate to the upper and lower parts of the wheel and the lower electrical resistance separates the higher electrical resistance proximate to the upper and lower parts;  
 each seal forming element being radially adjustable to vary the spacing between the spaced apart thermal seals; and wherein  
 the electrical heater is a film resistance disposed on a surface of the outer section which contacts the at least one web.  
 
     
     
       38. Apparatus for sealing at least one film ply to another film ply to at least partially form a chain of continuously moving, connected pouches, said apparatus comprising:
 a plurality of sealing elements, each including an outer sealing section one first thermal mass and an inner section coupled to a wheel, together with other inner sections of other outer sealing sections, said inner sections and wheel having a second thermal mass greater than the thermal mass of an outer sealing section;  
 a heater wholly disposed on said outer sealing section for heating said outer sealing section to engage and seal one said film ply to another when said one film ply is applied thereto; and  
 means for thermally insulating said outer sealing section from said inner section.